Place the flour and salt into a bowl and crumble in the yeast.
Place the milk into a pan over a low heat and warm through.
Pour the warm milk into the flour, mixing thoroughly to form a thick batter. Set aside for one hour.
Whisk the egg whites until soft peaks form when the whisk is removed.
Fold the egg whites and chives into the batter mixture.
Heat a small amount of the olive oil in a frying pan over a medium heat.
Add a spoonful of the batter and fry for 45-60 seconds, until golden underneath, then turn over and cook for 30 seconds on the other side. Remove the blini and place onto kitchen paper. Repeat this process with the remaining batter. Keep the blinis warm.
To serve, place a spoonful of sour cream onto each blini, top with a spoonful of caviar and arrange on a large serving plate.